1. Field of the Invention
The present invention relates to a clean room smock, and more particularly, to a clean room smock having an integral air passage for preventing contamination of a clean room and processing equipment located in the clean room, caused by particles generated from the human body.
2. Description of the Related Art
As the desire for higher quality devices and higher device production yields continue to increase, so does the demand for highly-purified and germ-free production environments for manufacturing such devices.
The two main types of production environments are Bio Clean Rooms (BCRs), for preventing biological contamination in medicine, food, genetically engineered products, etc., and Industrial Clean Rooms (ICRs), for preventing particle contamination in the semiconductor device, electronics, and precision machinery industries.
In semiconductor device manufacturing clean rooms, clean air flows through a filter in the upper portion of the clean room, then downwardly toward the lower portion of the clean room, and finally through a grating supporting production equipment located thereon, before being discharged and recirculated.
In addition to the clean room structure itself, the clothing or smock worn by the workers and equipment operators in the clean room is also very important in reducing particle contamination. The clean room smock prevents particles from the human body from entering the clean room environment, thereby reducing contamination.
The material for the smock is chosen based on such considerations as wearing-comfort, particle filtration efficiency, particle generation barriers, etc. In general, the conventional smock materials have provided high particle filtration efficiency and low particle generation, but the comfort of the operator is compromised somewhat in the process.
In FIG. 1 the conventional clean room smock 10 comprises an upper part 12 to cover the upper body above the waist, and a lower part 14 to cover the lower body below the waist. Normally, the upper part 12 and the lower part 14 are integrally formed. For wearing-comfort, a belt member 16, such as elastic band, is threaded through a normal belt ring 18 and conforms to the waist of the operator.
An opening/closing part 20 is formed on a certain portion of the upper part 12 so that an operator can easily put on the smock. In order prevent the air and particles from coming out of the smock while the operator is performing job tasks, an elastic band or similar means is provided at the openings for the neck line 22, wrist line 24 and ankle line 26.
The material for the smock 10 is highly dense to prevent air filtration from the inside to the outside of the smock, and accordingly, the pressure inside the smock is higher than that outside the smock because of the activity of the operator.
In addition, inside the smock itself, the pressure of the upper part 12 is higher than that of the lower part 14 because the upper part 12 and the lower part 14 are separated by the belt member 16, and the upper body of the operator experiences more activity that the lower body.
The air inside the smock, intermixed with particles from the body, flows to the outside of the smock due to the pressure difference between the inside and the outside the smock, or the pressure difference between the inner upper part 12 and the inner lower part 14, especially, through the openings for the neck line 22, wrist line 24, or zipper of the opening/closing part 20, as well as the seams of the smock.
For ease of handling and comfort, the processing equipment or devices in the clean room are usually located at heights equivalent to those of the upper body of an operator, and thus the equipment and devices are contaminated by the particles emanating from inside the upper part 12 of the smock.
In addition, the pressure difference creates static electricity due to friction between the body and the smock, which causes particles having electrical polarity to adhere to the outer surface of the smock, thereby increasing the likelihood of contamination of the equipment or devices.